Exosomes are important mediators of intercellular communication. They are also important biomarkers in the diagnosis and prognosis of many diseases, such as cancer. As drug delivery vehicles, exosomes offer many advantages over traditional drug delivery methods as a new treatment modality in many therapeutic areas.
The use of exosomes for therapeutic purposes requires that exosomes be free or mostly free of impurities including but not limited to contaminant proteins, DNA, carbohydrates, and lipids. Current purification methods do not offer sufficient selectivity to remove significant amounts of these impurities so additional processes are desired to improve purity.
Furthermore, as exosomes become more frequently used in the treatment of human disease, they may struggle to meet clinical expectations because of heterogeneity in their physicochemical parameters that confer molecular targeting, immune evasion, and controlled drug release. This is mainly due to the heterogeneity and complexity of exosome properties (e.g., composition, size, shape, rigidity, surface charge, hydrophilicity, stability, and ligand type and density), payload properties (e.g., drug type, solubility, loading, potency, dosing, immune response, and release kinetics), and in vivo physiological barriers to exosome trafficking (e.g., immune surveillance, particle extravasation, tissue targeting, tissue penetration, and cellular uptake). Although a considerable amount of effort has been made, effective methods for obtaining discrete sub-populations of therapeutic exosomes with desired properties, e.g., exosomes containing therapeutic payloads and having appropriate targeting moieties, are not yet readily available.
Suitable methods for generating, isolating and purifying discrete sub-populations of exosomes are needed to better enable therapeutic use and other applications of exosome-based technologies.